1. Field of the Invention
The invention relates to a fast-forwarding lock for a cassette for magnetic tape, and more particularly to a video tape cassette having a mechanism for preventing fast-forwarding of the video tape.
2. Description of the Prior Art
Video cassette releases have become an increasingly important source of income for the film industry. One source of revenue in the video market is advertising. But the value and effectiveness of advertising on a commercially-recorded video cassette is lessened by the ease with which a video can be fast-forwarded past any advertisements. Preventing such fast-forwarding would increase the value of the advertising time. Preventing fast-forward movement of copyrighted tapes can also prevent the potential use of high-speed duplicating machines for purposes of copyright violation.
A method of preventing fast-forwarding in a video cassette is disclosed in U.S. Pat. No. 5,005,099 of Perryman et al. In the '099 Patent, a light source is mounted inside the cassette casing. The light source is powered by a battery or by a generator driven by the movement of the tape reels, which battery or generator must also be built into the cassette casing. If the light is battery powered, the light is controlled by a mechanical tension-sensing switch. If the light is generator powered, it is controlled by the speed of the generator, i.e., by the speed of the tape wheels. In either case, when the light shines it activates standard photoelectric circuitry in the video cassette recorder (VCR) which stops the VCR.
This prior art method is rather complex. It involves electrical, mechanical, and, in the battery powered version, chemical components. This complexity poses two problems. First, reliability is a problem because this stopping method depends on the proper functioning of many components, some of which are themselves rather complex, as in the battery or the generator. Second, the number and complexity of the individual components makes the device expensive to manufacture.